Blastocystis is one of the commonest enteric protozoa in many hosts. This study evaluated
the effect of silver nanoparticles (AgNps) loaded with metronidazole (MTZ) on mice infected
with Blastocystis. They were subjected to parasitological, histopathological, immunological,
and immunohistochemical studies. The parasitological results revealed a powerful effect of Ag
NPs loaded with MTZ over either MTZ or Ag Nps; where the reduction of cysts count in stool
were (90. 7%, 87.33% & 59.33%) respectively as compared to infected non-treated group. Histopathological
results showed that AgNPs loaded with MTZ were the best in reducing inflammatory
changes followed by MTZ then AgNPs. Regarding IgA, IgM & IgG, Ag NPs loaded
with MTZ treated mice showed the best result followed by MTZ treated mice then Ag NPs
treated mice; where the reduction of mean concentration of IgA were (30.5%, 26.24% &
2.13%) respectively, while that of IgM were (15.2%, 12.8% & 2.8%) respectively and IgG were
(23.1%, 12.3% & 5.2%) respectively as compared to infected non-treated group. The synergistic
effect of both Ag NPS & MTZ provoked the best reduction of CD3 & CD20 expression and
augmented counter modulation of the immune response to restore normal immune homeostasis.